Characterization of coal before and after supercritical CO₂ exposure via feature relocation using field-emission scanning electron microscopy

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• 作者：Barbara G. Kutchko^a ; Angela L. Goodman^a ; ^{angela.goodman@netl.doe.gov} ; Eilis Rosenbaum^a ; Sittichai Natesakhawat^a ; ^b ; Keith Wagner^c
• 关键词：Coal structure ; Carbon sequestration ; Scanning electron microscopy ; Storage ; Macrospheres
• 刊名：Fuel
• 出版年：2013
• 出版时间：May, 2013
• 年：2013
• 卷：107
• 期：Complete
• 页码：777-786
• 全文大小：2262 K

文摘

The solvent and swelling effects of supercritical CO₂ on coal structure and porosity were examined using high-resolution field-emission scanning electron microscopy (FE-SEM) and surface area techniques to investigate any irreversible CO₂ induced alterations of the micro-, meso-, and macropores. Dry, 1 in. unconfined cores of Pittsburgh and Sewickly bituminous coals were exposed to supercritical CO₂ at 15.3 MPa (2200 psig) and 328 K (55 ¡ãC) for 104 days. Prior to CO₂ exposure, coal structure and porosity - specifically macropores (>50 nm) - were imaged using FE-SEM. After CO₂ exposure, the imaged features were relocated, reimaged, and analyzed for structural changes. Brunauer-Emmett-Teller (BET) surface areas were evaluated from the adsorption isotherms of N₂ at 77 K and P/P₀ = 0.1-0.3. Micropore surface areas were determined from the low-pressure adsorption isotherms of CO₂ at 293 K using the Dubinin-Polanyi equation. FE-SEM analysis indicated that there were no significant changes observed in the pore areas in all coal samples after CO₂ exposure. Meso- and micropore characteristics were slightly affected by supercritical CO₂ exposure.